(1) Field of the Invention
The present invention relates to a three-dimensional free motion apparatus, and particularly to a three-dimensional free motion apparatus which can be utilized as a simulation-experimental apparatus under an agravic environment capable of simulating a free motion under the agravic environment, or as an evaluation and test apparatus for a work robot for handling various flexible articles.
(2) Description of the Prior Art
In developments of remote automatic assembling technologies for structures in a space base, space robots for recovering an artificial satellite on the orbit, and the like, it is an indispensable matter to recognize movements of a target satellite and a chaser satellite due to the free motion at the time of docking of said satellites. In the past, various apparatuses for simulating the free motion by a hardware model other than the simulation by way of a motion equation model using a computer have been proposed.
Conventional methods for simulating a free motion under the agravic environment on the earth include (1) an underwater buoyancy system wherein a specimen model is put underwater and the balance of buoyancy is utilized underwater, (2) a suspension balance system wherein a suspension mechanism is combined into a three-dimensional traverse mechanism to utilize a cooperative operation, (3) a multiaxis active control system wherein an object is mounted on an active type motion mechanism in which a multiaxis force/torque sensor is combined with a three-dimensional traverse mechanism, and a servo feedback control is performed so as to cancel a reaction applied to a point of application, and (4) as a method for obtaining a real agravic state in the air, a ballistic flight system using an aircraft or a rocket and a free drop system by way of a drop tower.
However, these conventional systems have the problems as noted below.
(1) In the aforementioned method (1), the buoyancy should be adjusted according to the depth, and since water is used for a buoyancy medium, the water-viscosity affects on the movement, giving rise to a great difference in operation as compared to that under the vacuum environment.
(2) The aforementioned method (2) has a problem in that a compound motion is liable to occur between a suspension fulcrum and a specimen model, and since a sliding friction and an inertia of a 3-axis moving mechanism are great, a complicated movement occurs in the specimen model, failing to simulate the three-dimensional movement.
(3) The aforementioned method (3) has a problem in that the movement is not smooth due to the sensor noise, the inertia force of the mechanism portion, the play or looseness and the delay in control law resulting from the computation speed.
(4) in the aforementioned method (4), the experiment is large-scaled whilst the time is short. This method can be merely applied to the test such as confirmation of behavior by a small type apparatus, and is not suitable for the test for establishment of the elementary technology of a control apparatus having a large type mechanical portion.
On the other hand, the aforementioned conventional three-dimensional free motion simulation apparatus has been merely proposed as a simulation means for the work under the agravic environment, and as an experimental apparatus exclusively for the development of the space such as a space robot. However, a three-dimensional free motion apparatus has not yet been proposed for various applications on the ground, for example, for an evaluation stand or the like, in the development of a robot for handling flexible articles, for simulating a degree of impact or the like applied by the robot to an object to evaluate a flexibility of the robot.
The conventional robot generally employs a multi-articulated arm mechanism and controls the movement by information from a sensor or the like and a predetermined control law. However, this robot has a limitation in terms of mechanism, operating properties and the like, and involves a danger. There still remains a problem not solved for a robot which is gentle with animals and plants including a human being, easily-breakable articles such as glass work, and other flexible articles. Studies on the harmonization between these various conventional type robots and the human being and the like are a future theme. Particularly, the development of a nursing robot to meet people of the great age is an important theme.
In the development of these robots, there has been empolyed a system in which the relationship is established before hand between individual objects such as a human being, flexible articles and the like to determine a gripping pressure, a contact pressure and a control law for a movement or the like. These evaluations are merely applied exclusively to fixed objects. And, there is no apparatus capable of evaluating a true flexibility in the robot. Such an apparatus has been desired to be developed.